Tuning a temperature controller involved in a heater used in the process for forming a semiconductor device or other electronic device is typically performed based on a liner relationship between the temperature and the resistance or a liner relationship between the temperature and the voltage of the heater. However, as the fabrication steps in semiconductor technology become more complicated, it gets harder to monitor the operating condition of the heater step by step. The heater thus may either be prematurely replaced before it gets out of order or be tardily replaced after the performance thereof gets out of hand. Unnecessary cost, on one hand, may occur due to the premature replacement of the heater; the fabricating process, on the other hand, may fail due to the failure performance of the tardily replaced heater.
Therefore, there is a need of providing a heater condition monitoring and accessing method and applications thereof to estimate the remaining useful life of the heater under test and to replace it at the optimum replacement point.